I think Kagome could also be a very powerful character in a crossover. She has the power of the Shikon Jewel and her spiritual powers are constantly growing. In a crossover, she could potentially combine her powers with the technology or spiritual knowledge from the Bleach world. For example, she could use her spiritual arrows in new ways with the help of Soul Reaper techniques. Also, her ability to travel between the two worlds could give her an advantage in terms of strategy and knowledge gathering.
In my opinion, Aizen could be one of the most powerful characters in such a crossover. His intelligence and his ability to manipulate others are already very dangerous in the Bleach universe. If he were to enter the Inuyasha world, he could easily use his wits to turn the different factions against each other. He could also potentially find a way to use the demon energy for his own gain. His Zanpakuto's powers are also very versatile and could give him an edge against the characters in Inuyasha's world.
Sesshomaru could also be a very powerful character in this crossover. He has his own powerful sword, Bakusaiga, and his inhuman strength and speed. He is very experienced in combat against demons. Compared to Naruto's friends like Sakura, Sesshomaru would likely be much more powerful in terms of raw strength and combat ability. But Sakura has her own medical ninjutsu and superhuman strength when she releases her inner power, which could also be useful in different situations.
Ichigo and Inuyasha would be a very interesting pair. Ichigo has his inner Hollow and his strong sense of justice. Inuyasha is a half - demon with a short temper but also a good heart. Their interactions would be full of clashes and also mutual respect as they both fight against evil in their own ways.
It's really hard to say who would be the most powerful. Saitama from One Punch Man (if we were to include him in this wild crossover thought experiment) would probably be a top contender just because he can defeat any opponent with one punch. But in a more traditional Bleach - Marvel crossover, if the Living Tribunal from Marvel was involved, it would be extremely powerful. It has near - omnipotent powers and oversees the entire Marvel multiverse. However, in Bleach, Yhwach has extremely powerful abilities as well, like the ability to see the future and rewrite it. So it really depends on the context and how the crossover is set up.
It's hard to say for sure. Naruto in his Sage Mode or with the power of the Nine - Tails is extremely powerful. He has a vast amount of chakra and can perform powerful jutsus. However, Inuyasha with his Tessaiga, especially when it's in its upgraded forms, is also a force to be reckoned with. He has superhuman strength and speed, and the Tessaiga can cut through almost anything. But if we consider all aspects, Naruto might have an edge as he can use a wider variety of techniques and has more experience in large - scale battles.
It's likely to be Goku. His ability to constantly increase his power level through training and reaching new forms like Super Saiyan God and Ultra Instinct gives him an edge. He could potentially overpower most of the Bleach characters.
It's a tough call, but it could be Light. If he manages to get his hands on the knowledge of the Inuyasha world and its rules, he could use the Death Note very effectively. He could target demons by learning their names, and since many demons in the Inuyasha world are vulnerable to human - like weaknesses in some ways, his strategic mind could make him a very powerful force. He could even manipulate some of the human characters in the Inuyasha world to do his bidding.
But we also can't forget about Ichigo in his final form. He has the power of a Soul King and his combat skills are top - notch. If he were to enter the Fairy Tail world with all his power, he would be able to take on most threats with ease. It really depends on how the crossover is written and what kind of challenges are presented to each character.
It's hard to say for sure, but Ichigo could be a very powerful character in this crossover. He has his Hollow powers, his Soul Reaper powers, and his Quincy powers all combined. In a fight against the powerful characters from Soul Eater, like Asura, his multiple power sources would give him an edge. He can quickly adapt to different situations and opponents, and his high - speed attacks and strong spiritual pressure would be difficult for many to handle.
It's a tough call, but it could be Luffy. His Devil Fruit powers combined with his indomitable will make him extremely formidable. If he were to somehow gain some Soul Reaper abilities on top of that, like the ability to use a Zanpakuto, he would be near - unbeatable. His Gear Fourth form already gives him enhanced strength and speed, and with Soul Reaper powers, he could be a force to be reckoned with.
It's hard to say for sure, but Ichigo from 'Bleach' could be a strong contender. His Hollowfication gives him a huge boost in power, and his Bankai is extremely powerful. In the world of 'Familiar of Zero', his powers would be very hard to counter. However, Louise with her Void magic also has the potential to be very powerful. Her magic is unique and can be extremely destructive when she manages to control it properly.